The quality of mortar directly affects the durability and aesthetics of a building. However, in actual construction, mortar often encounters some quality problems, such as drying time, coarseness and fineness, stone mixing and viscosity problems. This paper will discuss these common problems and their solutions in detail to help constructors improve the use of mortar.
Drying time of plastering mortar on the wall
The drying time of plastering mortar is affected by the degree of water absorption on the wall, water retention of mortar, mortar setting time and environmental humidity.
The humidity of the wall surface is normal and the air humidity is normal and the construction thickness is within 2cm
In this case, the drying time of the plastering mortar is normal, consistent with the mortar mixed on site, and able to meet the requirements for use on most sites.
The humidity of the wall surface is very high or the humidity of the air is very high or the construction thickness is more than 2cm.
If the wall humidity or air humidity is very high, or the construction thickness is more than 2cm, the drying time of the mortar is 1 to 3 hours longer than that of the mortar mixed on site.
Very high humidity of the wall surface and high air humidity and the construction thickness exceeds 2cm
In this case, the drying time of the mortar will be very long and may seriously affect the construction progress.
Solution
Drench the wall of the site 1-2 days in advance to increase the water absorption of the mortar on the wall.
For the construction of very thick parts of the first advance slurry to a certain thickness (1~2cm), to be the next day a one-time leveling.
Shorten the opening time of the mortar, so that the mortar quickly reach the setting time and shorten the drying time.
Problem of mortar thickness
The thickness of mortar is mainly affected by the thickness of sand. Too coarse or too fine mortar will have a negative impact on the construction effect.
Problem of too coarse mortar
If the mortar is too coarse, the surface will be rough when the workers work, and it is not easy to smooth out, which will affect the aesthetics.
Problem of too fine mortar
If the mortar is too fine, the workers will smear the wall too thinly at one time, which will affect the construction progress and reduce the hardness of the hardened mortar surface.
Solution
Before production, we should go to the sand yard to judge the thickness of sand, and control the fineness modulus of sand at 2.4~2.7 as the best.
Problem of stones in mortar
The presence of large stones in mortar will seriously affect its usability and may lead to construction quality problems.
Source of stones
Stones are mainly mixed into mortar through the following ways:
mixers
sand quarries
Mixer trucks
Upper sand floor bin and belt
Intermediate sand hopper
Sand Screener
Solution
Strictly clean the sand in the machine.
Reinforce the work consciousness of the shovel driver to avoid mixing stones when shoveling sand.
Make sure the mixer truck is cleaned inside.
Strictly clean the upper sand floor bin and the belt.
Avoid different material hoppers being too close to each other and make sure there are no perforations in the sand hopper walls.
Regularly check the screen mesh of the sand sifter to avoid fluctuation in the quality of sand caused by breakage.
Viscosity problem
The viscosity of mortar directly affects its construction performance, the normal viscosity of the mortar construction is smooth, and it is not easy to fall off the wall.
Winter viscosity problem
In winter, the viscosity of mortar increases, and it is necessary to reduce the dosage of viscosity additives accordingly.
Summer viscosity problem
High temperature in summer, mortar viscosity decreases, need to increase the dosage of viscosity additives.
Influence of stone powder on viscosity
Too many impurities in stone powder will lead to poor viscosity of mortar, and the whiteness of stone powder should be controlled above 40 degrees.
Solution
Adjust the dosage of viscosity admixture, generally every 5 degrees of temperature increase or decrease, the dosage of admixture should be increased or decreased 1kg/m³ accordingly.
Conclusion
The common quality problems of mortar in the construction process mainly include drying time, coarseness and fineness, stone mixing and viscosity problems. By taking appropriate measures, the construction effect of mortar can be effectively improved to ensure the quality and aesthetics of the building.
Frequently Asked Questions (FAQs)
Why does the drying time of mortar vary?
The drying time of mortar is affected by the humidity of the wall surface, air humidity, thickness of the construction and other factors, and the drying time varies under different circumstances.
How to control the coarseness of mortar?
The coarseness and fineness of mortar can be effectively controlled by going to the sand yard to judge the coarseness and fineness of sand in advance and controlling the fineness modulus at 2.4~2.7.
What is the reason for the appearance of stones in mortar?
The appearance of stones in mortar is mainly due to the mixing of stones from mixers, sand yards, mixer trucks, upper sand floor bins and belts, intermediate sand hoppers, sand sifters and other ways.
How does the viscosity of mortar affect construction?
The viscosity of mortar directly affects the smoothness of construction, too low viscosity is easy to drop slurry, too high viscosity is not easy to dry, will affect the construction effect.
How to adjust the viscosity of mortar in different seasons?
In winter, the dosage of viscosity additives should be reduced, and in summer, the dosage of viscosity additives should be increased, and the specific dosage should be adjusted according to the temperature change.